Corsican Geology: An excursion guide based on the G.A. trip toCorsica June 25th-July 2nd 1983

w. Gibbons

Department of Geology, University College, P.O. Box 78, CardIff CFl l XL. u.s.

1. INTRODUCTION TO THE GEOLOGY OFCORSICA

The island of Corsica lies in the Western Mediterra­nean , 160 km SE of Nice , between the deep Liguriansea (W) and the Tyrrhenian sea (E). Althoughpolit ically the island belongs to France , geologically itforms the northern part of the Co rsa rdinian massif(Fig . l)-a microplate which sepa rated from theEuro pean continent during the middle Tert iary.

Corsica is broadly separable into two unequalgeo logical unit s (Dura nd-Delga, 1975): to the W and Sis 'Hercynian Corsica', dom inated by Carbo niferouscalc-a lkaline granitic rocks, whereas to the NE arepolydeformed schists belonging to 'A lpine Corsica'(Fig. 2) . Th e contact be tween these two major units istecton ic, being marked by a major shear zoneprodu ced as the Alpine schists were obducted on tothe Hercynian basement during the late Cretaceous(Mattauer et al. , 1981).

(a) Palaeozoic

Rocks of Palaeozoic age are confined to HercynianCorsica except where slices of the Hercynian basementhave been caught up within the Alpine schists. Most ofthe Hercynian basement is composed of a vast ,compound granite batholith mor e than 400 km long ,running fro m the SE of Sardinia to the NW of Corsicaand intruded during the Lower Ca rbo niferous. Thecountry rock into which these granites was intruded ispre served in very few places in Corsica and consists ofPre cambrian gneisses and Lower Palaeozoic sedi­ments . Th e Corsardinian granites are overlainunconformably by U. Carboniferous sediments andlocally by a thick series of acid extrusives andvolcaniclastics of Lowe r Permian age . An othernot able fea ture of this Permian igneous activity is aser ies of ring dykes which cut the gra nite (Maluski,1976). .

(b) Mesozoic

Th ere are very few Mesozo ic rocks remamm g onHercynian Corsica. However , there are preserved afew outliers of Triassic and Jurassic marine limestoneswhich ind icate that Corsica was submerged beneaththe shelf of the expanding Tethyan Ocean when seafloor sprea ding was opening up the South Atlantic,and Africa was moving sinistrally agai nst Eurasia and

North America. During the Cretaceo us, Eurasiabegan to sepa rate from N. Am er ica and the relativemovement between Africa and Eu rope became dextraland compressiona l. It has been suggested (e .g.Zachar , 1979) that about this time an intra -oceanicsubduction system collided with Corsardini an massif(90-100 Ma) obducting the schists of Alp ine Corsicaover the Hercynian basement (Mattauer & Proust,1976).

The Alpine schists include various Cretaceoussediment s once deposited in the Tethy an Ocean(limestones, pelites, cherts and quartzites) andJurassic to Cretaceo us ophiolites (pillow lavas,gabbros, serpentinites) , as well as allochthonoussliver s of strongly deformed Hercynian baseme nt.Many of the se schists show evidence for several phasesof deform at ion , the earliest of which were the mostintense and developed during blueschist faciesmet amorphism (Du Ch affaut et al. , 1976) . Th ismetam orphism has been dated by radio met ricmethods (40Ar/39Ar and 87R b/86Sr) as 80- 100 Ma(Cohen et al. , 1981; Maluski, 1977). The schistsprod uced during this eve nt are analogo us to the broadbelt of coeval schistes lustres of the intern al Piedm ontZone of the Western Alps . In particular , the Corsicanschistes lustres have been correlated with the Volt riGroup which cro ps out along the Itali an coast west ofGenoa (du Chaffaut et al., 1972; Moullade , 1978;Messiga et al. , 1983) .

(c) Cenozoic

The early Terti ary appears to have been a time ofuplift of the blueschists , rapidly enough to avoid anymaj or ove rprint of higher temperature assemblagesupon the high P/low T phases. Renewed sedimenta­tion occurred in the Eocene when a marinetransgression deposited a basal conglomerate , lime­stones then deeper water flysch (Routhier, 1956; DuChaffaut , 1973). These Eocene deposits, whichinclud e olistos tro mes, were precursors to a generalph ase of instability and deformation dur ing the lateEocene-earl y Oligocene when nappes were moving offfrom the upri sing internal Alps.

During the Oligocene the Corsardinian microplatecame into being and palaeomagnetic studies indicatethat it rot ated SE anticlockwise away from Pro vence,opening the Ligurian sea (Nairn & Westphal , 1968;Auzende et al. , 1973; Alvarez, 1972; Westph al et al. ,

171

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Fig. 1. Geol ogical ske tch map of the Alpin e system (after Frey et al. 1974; Moullade, 1978; Miller et al. 19R2).1 = Perm o-Mesozoic -Tertiary cover to Extern al Western A lps (Helvetics); 2 = Pre -Alpine crystalline basement (includesPerm o-Carb oniferous cover in Corsica and S. Provence) ; 3 = Penninic dom ain-including the Mesozoic high P meta sedimentsand ophiolites of schistes lustres ; 4 = Pre-Triassic basement beneath Penn inic schists (also affected by high P metamorphism);5 = Austroalpine dom ain and Sout hern Alps; tm = Tenda Massif; dm = Dora Maira : gp = Gran Paradiso ; mr = Monte Rosa;t = Tauern Window; vg = voltri group. From Gibbons & Horak (1984), with permission.

CO RS IC A FI ELD MEETIN G 173

Fig. 2. Geological sketch map of Co rsica. I = MostlyHercynian granite basement ; 2 = Shea red granitic basement ;3 = schistes lustres and ophiolites; 4 = autoc hthonoussedimentary cover on 1; 5 = Mioce ne sediments ; BN= Balagne nappe; NN = Nebbio nappe; MN = Macinaggionappe; SLN = Santa Lucie napp e; EC = Ecailles Cor te­naises.

1973; Chabrier & Mascle 1975; Arthaud & Matte,1975; Vanden berg & Zijderveld , 1982). Otherevidence for this rotation includes: 1) similar Perm ianigneous rocks and Lower Palaeozoic fossils inCorsardini a and the Esterel massif of S. Provence(Fig. 1) ; 2) the occurrence of Lower Cretaceousbauxite in both Sardinia and W. Provence; 3)volcanism associated with the break-up occurred alongENE- WSW faults parallel to the French coast.

The Lower Miocene saw a marine tra nsgressionfrom the south lapping over the margins of the nowsepa rated microcontinent. Miocene rocks are pre­served in four places on Corsica (Fig. 2): at St. Florentand Bonifacio (shallow marine limestones) , Fra ncardo(intermontane basin sediments) and on the Aleriaplain (shallow marine marls and conglomera tes) . Thelatt er exposures occur on the west edge of the faultcontro lled Tyrrhenian basin in which up to 8 km ofMiocene sediments were deposited (Boccalett i &Manetti, 1978). The middle Miocene littoral lime­stones of St. Florent and Bonafacio include spectacu­lar cross-bedded bioclastic un its, reef deposits andrhodolith ic horizons.

8 2

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A period of volcanicity occurred in late Oligoce ne­Miocene times and may have been relate d to atransient period of plate subduction along a westdipping Benioff zone (Ho rvath & Berckhemer, 1982).Present day exposures of these volcanic rocks aremostly confined to Sardinia, the only Corsica nevidence being a small outcrop of ignimbrite preservedin the extre me south of the Island .

2. ITI NERARY

On 25th Ju ne 1983 22 memb ers of the Geo logists'Association met at Calvi airport. During the hot andsometimes stormy wee k that followed the groupmoved east then south, staying at hotels in Calvi, St.Florent , Cor te and Solenzara. The trip was to provean eventful one, with the sudden death from naturalcauses of one of the party, Harold Grieve, in themountains above the Restonica gorge. Despite theshock and sadness felt by the party over this tragicincident , the trip was in all oth er respects a success.

The 7 day itinerary outlined below is that followed ,with minor amendments, by the G.A . party (Fig. 3) .The route can only be followed by those with privatecar or minibus. The itinerary covers most aspects ofCorsican geology and provides the additional oppor­tun ity to travel widely across the Island and to visitseveral sites of historical and archaeo logical interest.All necessary maps may be obtained from McCar taLtd ., 122 Kings Cross Road , Lond on WCIX 9DS .

Excursion 1: Calvi to St. Florent (92 km)

The object of this day's excursio n is to make a west toeast traverse from the gra nitic basement of HercynianCorsica to the metamorphic rocks of Alpine Corsica.The route also visits exposures of autocht hono usEocene sediments which rest upon the grani ticbasement . Figure 4 illustra tes the main features seenon this traverse. In the Calvi area a series of potassicgranites intrude the slightly older granit ic plutonswhich dominate the geology of W. Corsica (Durand­Delga, 1978). East of Lozari one reaches Eocenesediments beyond which the autochthonous basementis raised once again to view by a major fault . This areaof mostly granit ic basement is known as the TendaMassif, and forms a broad ant iclinal dome . Whilst thecentre of this massif is unaltered, the flanks(particularly the easte rn one) are strongly affected byAlpine (late Cre taceo us) deformatio n and meta­morphism. Thu s, moving E from the central Tenda,one passes up thro ugh a zone of severely mylonitisedgranites to reach the overlying metamorphic rocks ofthe schistes lustres just W of St. Florent (Fig. 4) .1.1 Calvi is built on biotite grani te, often containinglarge zoned K-feldspar crysta ls, xenoliths andpro minen t sphene crysta ls. Dykes of doleri te andaplite, and quartz-epi dote veins all cut the granite ,which belongs to the late , potassium-rich suite

174 W. GIBBONS

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Calvi

Fig. 3. Excursion route map.

intruded into the calc-alkaline granitic base me nt ofNW Corsica. Excellent exposures of granite may beexamined along the cliffline around the port , belowth e SE corner of the 13th Century Ge noese citade l.South of the wide , sandy Gulf of Calvi rise mountainsof granite and Permian volcanics- the highest pointbeing Mt. Cinto (2710 m), 25 km to the SE . Thero lling hills and plains Sand E of Ca lvi form an areaknow n as the Balagne . It is scenically one of th e mostdiverse regions of Corsica , with patchwork s ofterraced fields and plantati on s, num erous hilltopvillages and coastal towns.1.2 Leaving Calvi, tra vel E aro und the wide bay,with goo d exposures of Quaternary raised beach alon g

the roa dside afte r 2 km. By-pass Algajola (15 krn) ,another Genoese coastal fortress , and afte r 2 km turnleft along a poorly defined track (a few hundredmetres beyond a petrol sta tion on the left) . A fiveminute walk along this track leads (left ) to a sma llquarry containing an enormo us gra nite column(17.5 m long and 2.5 m in diameter ) known locally asthe Monolith. Th e column was "intended to form th ebase of a statue of Napo leo n in Ajaccio , but its 300ton s proved too heavy to lift and transport.1.3 Continue eastwa rd over the granitic basement6 km eas t of lie Rousse (named after exposur es ofleucocratic red gra nite) , stop whe re the road turnssouth for a good view towards the Eocene sedimentswhich form the hills to the eas t (the 'Ba lagnesediment aire').1.4 Aft er 1km , beyond the junction to Belg odere,the ro ad narrows and turns NW , hugging theprecipitous coastline as it climbs up on to theautochthonous Eocene sediments of the Balagnewhich rest unconformably upon the Herc ynian granite.The Eocene succession is: basal cong lomera tes,overl ain by sands to nes and calcareo us marls, then agre at thickness of flysch . Exposure s of the flysch oftensho w good sedime nta ry struc tures (grading, loadcasts,etc .) and eviden ce for syn-sedimenta ry deformat ionproduced by slumping over a weste rly dipping seafloor. Altho ugh th e unconformity is not exposed ther eis an exce llent expo sure of flysch in th e cliff by a smallparking space (right) approx. 2.5 km NW of thejunction with the roa d to Belgodere .1.5 Furt her eas t the road leaves the coast anddescends SE into th e wide Ostriconi Valley. Th e valleyis und erl ain by Quaternary alluvium and per iglacialsediment, with blown sand on the E side , and marksth e line of the major Petra- Monet a fault-theboundary between the Balagne and the Tenda massif.

Th e Tenda Massif is crossed by only one roa d whichwind s tortu ously through the barren desert desAgriates for ove r 20 km. The granite expos ures areoften wea thered in a peculiarly macabr e mann er-aneffect resulting from the differential erosion of soft,altered granit e , leaving a framework of relativelyhard , th in siliceous veins.1.6 It is inst ructive to begin a traverse fro m unalteredgranitic rocks in the core of the Tenda massif andmove eas t towards the Alpine schists. Ex posur es ofweathered , xeno lithic hornblende granodiorite cut bybasic dykes can be exa mined in a grave l qu arry (right)just E of Casta (before a small church on the left ). Atthis deep level one is approx imately 1 km below theschistes lustres nappe and th e Tenda baseme nt isvirtually unalter ed by Alpine metamorphism (Fig. 5) .1.7 Moving east from thi s location the granodio ritebecomes progressively shea red and metam orphosed. Itdevelops an easterl y dipping mylonitic foliation andundergoes seve ra l complex mineralogical changes(Gibbons & Hor ak , 1984) . Th e primary biot ite breaks

CO RSIC A FI ELD M E ET ING 175

BastiaGSt. Florent

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------- Alpine Corsica

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Fig. 4. Geological sketch map and cross section of N. Corsica (afte r Durand-D elga, 1978).

down to chlorite or muscovite and the hornblendeconverts to ferro-actinolite (Ca Amph on Fig. 5).Approximately 1.5 km further east (be yond a smallbar/hotel on the left) the sheared granitic rocks and, inparticular, the basic dykes begin to develop blue,crossitic amphiboles from primary hornbl ende (NaAmph on Fig. 5). From this point eastwards only blueamphibole are found as one moves up towards theoverlying blueschist facies schistes lustres. Along theroadside are many exposures of shea red granites witha mylonitic foliation gently warped by late (F3) ,

north- south folding (Fig. 4). Blue amphibole bearingmeta-basic dykes in the granite may be examined inthe track leading up the west side of Monte Guppio.The best exposures of mylonitised granites are seen inthe quarry on the E side of Monte Guppio 500 mbeyond the road to Santo Pietro. At and above thislevel the mylonitic foliation , with an easterly plunginglineation , is strongly folded by SE verging F2 minorfolds, this second phase of deformation becoming

more and more intense as one moves towards theschistes lustres nappe (Mattuer et aI., 1981). There arefine views from here over the low lying synclinal areaknown as the Nebbio-an enclave of fertile lowlandbounded by the twin anticlines of the Tenda and themount ains of Cap Corse furth er east.1.8 Return westwards for 500 m and take the poorroad to Santo Pietro di Tend a , one of several ancienthill villages which rim the Nebbio syncline. Park bythe church and walk back 100 m or so to a trackrunn ing west along the south side of a valley beneaththe village (Fig. 6). The section allows examination ofthe schistes lustres lying immediately above themylonitised Tenda granites. The schistes lustres arerepresented by strongly folded and metamorph osedquartzites, limestones and mudstones. The obviousfolds in the metasediments deform an early foliat ion(Sj ) and are therefore F2 structures. Gentle F) foldsare also discernable in some exposures . Beyond thestrea m the mylonit ised granite is reached, and it can

176 W . G IBBONS

Fig. 6. Schistes lustres- my lonitised granite contact at SantoPietro di Te nda (locality 1.8) (af te r Dur and -Delga , 1978).

Fig. 5. Sketch map and cross-section of E. of Casta (locality1.6) showin g zonation from undeformed granodiorite (1) toCa-amphibole bearing protomylonite (2) to crossite bearingprotomylonite (3a). mylonite (3b) and overlying schisteslustres (4). S = synform; A = antiform. Ar rows indicate dipof myloniti c fabr ic. (afte r Gib bons & Horak , 1984).

conglomer ates which fill the core of the syncline in thelimestone. Good exposure s of the conglomerates maybe seen on the S side of the main road 100 m eas t ofthe Hotel Madame Mere.

Excursion 2: St. Florent, the Nehbio, and Bastia(53km)

The object of this excursion is to examine the geologyof the Nebbio syncline and the schistes lustres at the Send of Cap Corse between St. Florent and Bastia. TheNebbio syncline (Fig. 4) has preserved an allochtho­nous unit of ophiolit e and sedimentary rocks. Th erocks of this Nebbi o napp e include Palaeozoicmetasediments, Tri assic and Jur assic limestones andpillow lavas, and Cretaceous and Eocene conglomer­ate s and flysch, all of which were emplaced probablyduring the Oligocene. Unfo rtun ately, however ,exposures are generally very poor in this low lying,well cultivated ground. By contrast , the low mountainsof schistes lustres to the east which emerge frombeneath the Nebbio nappe provide both spectacularviews and excellent exposures of polydeformed andmetamorphosed Mesozoic ophi olites and sediments.2. 1 Walk along the track opp osite the Madam e Merehotel to reach the Genoese citadelle, and descend tothe beach to examine exposures of Miocenelimestones. The bed s dip ENE on the W limb of theSt. Florent syncline. The lowest part of the sequ ence isin places similar to the exposures seen in the town andcont ains superb examples of rhod oliths (algal concre­tions, often around a pebble nucleus). The rhod olithi climestones are overlain by cross-bedded , sandy,bioclastic limestones with good bioturbation struc­tures.2.2 Take the small road leading ESE from St.Florent , passing the Cathedrale du Nebbio-one ofthe two oldest build ings on Corsica. Built from whiteMiocene limesto ne by the Pisans in the 13th Century,it is characteri sed by extreme simplicity of style andplan (Romanesque) . The road enters a limestonegorge , passing down through the Miocene limestonesuccession to emerge on to the flat , cultivated land onthe Nebbio nappe. Small exposures of defo rmedallochth onous Eo cene conglomerates occur along theleft side of the road about 4 km from St. Florent. Theconglomerates cont ain man y clasts of pink , oftenporphyritic, Perm ian rhyolites.2.3 As the road turns south and begins to climb, onemoves down on to the basement beneath the Ne bbionapp es. The basement here is not typical schisteslustres , however, but a sliver of myloniti sed xenolithicgranite (the gneiss d'Oletta) caught up within theschistes lustres during Alpine deformation. Good ,strongly lineated exposures of this allochth onousHercynian basement can be examined in the roadsidejust beyond a sharp left turn into the road leading upto Col de Teghime .

c ae t a

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be seen that these display a similar structura l histor y tothe schistes lustres i.e. S, folded by F2 . If time allowscontinue for 1.5 km along the path to Bocca a Canali ,a fine viewpoint.1.9 Return to the quarry (Stop 1.6) and descendtowards St. Florent. The granite become s increasinglydeformed as one approaches the schistes lustres. Goodexposures occur around the town rubbi sh dump,beyond which the mylonitised granites are interl eavedwith serpentine. Exposures of serpentinite are seen ina quarry (right) further down the road . The schisteslustres in this area are represented mostly bymetamorphosed serpentinites , basic lavas and lime­stones.1.10 St. Florent is built upon white Miocenelimestone which is folded into a broad N plungingsyncline. The fossiliferous limestone is up to 400 mthick and was mostly deposited in shallow, warm water(littoral zone). Good expo sures may be seen in thetown near the gendarmerie (from the Post Office climbup the road towards the gend armerie). The limestoneshere contain red pebbles of grani te and rhyolites, andabundant shell fragments.

The youngest strata in the town is the river alluviumof the Aliso, and exposures of Quaternary fluvial

CO RSIC A FI ELD M E ETING 177

2.4 The road leading to the Col passes largeroadstone quarrie s in schistes lustres meta -limestones .Continue northwards and park (left) near the top ,where the road turns sharp ly to the east. From thissuperb viewpoint on the high ridge running N-S downCap Corse may be seen the whole of the Nebbioregion , with the Tenda massif rising further west. Notethe synclinally folded Miocene limestone aro und St.Florent-the fold is asymmetric with the E limbdipping more steeply than the W limb.

To the north rise the hills of Cap Corse (highestpoint 1307 m), the west side of which is composeddominantly of serpentinite with slivers of mylonitisedgrani tes, schistes lustres met asediments , gabbros andpillow lavas. All these rocks were metam orphosedunder blueschist facies conditi ons and form part of theenormous schistes lustres nappe, thrust over thegranitic basement of the European plate during themiddle to late Cretaceous. At this locality the schisteslustres are repr esented by metamorphosed limestonesthought to be of Jurassic age .2.5 Drive eas t over the Col (541 m). Park by a largedisused quarry 1 km NE of the Col where there aregood exposures of schistes lustres : polydeformedmarbles , quartzit es and pelites. The structure isdominated by a large , SE verging F2 antiform (withmany minor F2 folds) with later upright folds runningNNE-SSW.2.6 The road from here down to Bastia crosses moreschistes lustres on the E limb of the Cap Corseantiform with more slivers of mylonitised granite,sheared serp entinite and blueschists der ived frombasic lavas.

The town of Bastia is very much a commercialcentre and most of it lacks immediate charm . Themost interesting areas are found around the Old Portand the nearby Citadel. Leave the town and travelsouth along the western edge of a wide flat plainunderlain by Quaternary fluvial drift. The contactbetween this plain and the schistes lustres hills to thewest is a major fault.

After 9 km take a small road (right) just before arailway crossing and climb back onto the schisteslustres. The schistes lustres here contain large massesof serpentinite which are well exposed in severalquarries along the roadside.2.7 Continue west along the poorly maintained roadfor about j km, passing the hamlet of Cinquerne. to abridge and sharp left bend where the road crosses astream. Beautiful fresh specimens of blue glaucophaneschists may be collected here . The schists wereproduced during high P/l ow T metamorphism of basiclavas which once probably formed part of the Tethyanoceanic crust.2.8 The road enters the Lancome Gorge , carved intothe meta-ophiolitic rocks of the schistes lustres in thisarea, and eventually emerges at the Col de SanStefano. Turn right , re-entering the Nebbi o region

from its SE corn er. A short stop may be made in thevillage of Olmeta di Tuda where there is a good viewN towards S1. Florent . The prominent quarry inMonte Tuda just N of the village excavates UpperTriassic/Lower Jur assic limestones and dolomites ofthe Nebbio napp e . The limestones rest with a thrustcont act upon Eocene rocks.

The route continues past the quarry, descending tothe flat cultivat ed land beyond Oletta before enteringthe Miocene limestone hills just S of St. F1orent.

If time allows an excursion may be made along theW coast of Cap Corse (meta-ophiolites) as far as theabandoned asbestos quarries of Canari (27 km fromS1. Florent ) . The asbestos was quarr ied until 1964from a serpentinite bod y lying between two layers ofmet a-gabbro. An interesting and picturesque returnrout e is to take the narrow road to Patrimonio viaPoggio, skirting the NE edge of the Miocene syncline.

Excursion 3: St. Florent to Corte (80 km)

This excursion makes a N to S traverse across the highridge of schistes lustres bounding the Nebbio synclineto the S, then drop s down into the Golo Valley andskirts the southern edge of the Tenda massif. A drivefurther south toward s Corte then allows examinationof the less metamo rphosed allochthonous units such asthe Santa Lucia Nappe which lie faulted between theschistes lustres and Hercynian basement. Finally , onereaches the historic town of Corte , built on schisteslustres just E of the granite mountain of centralCorsica. The first part of the route involves driving onpoor roads and should not be attempted in badweather. An easier alternative is to take the main roadS from Bastia then E along the Gal a valley to PonteLeccia (Fig. 3) .3.1 Retrace the road past Olmeta-di-Tuda, andfollow the road towards Murato around the southernrim of the Nebbio region . The route passes thepicturesque 13th Century church of San Michele , builtfrom blocks of white limestone and dark bluesch ists.There are good views N towards St. Florent.3.2 Beyond Murata (metagabbro) the poor roadclimbs to the Col de Bigorno (885 m), passing manyexposures of serpentinite and losing its metalledsurface a few kilometres before the Col. In this areathe Jurassic met aophiolites separate a unit of upperschistes lustres from a lower one (De lcey, 1974).3.3 From the Col, the road begins the long 700 mdescent into the Gala Valley, crossing back down thesuccession from serpentinite to lower schistes lustres.The latter are exposed between Bigorno (turn sharpright) and Lento, and display F2 isoclines and F3upright folds. At Lento there are views eastwards tothe contact betwe en lower schistes lustres andoverlying serpentinites. In this area the lowest part(E rbajolo Fm .) of the upper schistes lustres (Inze cca

178 W. GI BBONS

Gp.) appears bet ween the lower schistes lustres andserpentinite (D ura nd-Delga , 1978, p . 56).3.4 The ro ute hugs the N slope of the Golo Va lley,roughly following the contact between the InzeccaG roup and the lower schistes lustres. Nearly 1 kmbeyond Costa Roda the ro ad turns W and crossesmore meta-ophiolites (basic lavas then serp entinite),skirting the S edge of the Tenda massif shea redgra nites , to reac h the valley bottom .

In thi s area the Golo Va lley separa tes the Tenda(N) from a region kno wn as th e Castagniccia (S) , thetopog raphy of which is dominated by radi al dr ain agewith steep rugged slopes. As a conse quence the area isa natural fortress and has tr adition ally been a bastionof Corsica n resistanc e and patrioti sm. More than an yothe r re gion , the Castagniccia reflects the island'seconomic and demographic decline. Most of the manyhilltop villages are half empty and decaying , with ameagre, aged po pulation , although many emigresfro m the region re turn home for their holidays in thesummer and to vote in ele ct ions .

G eo logica lly, most of the Castag niccia is aco ntinua tion of the schistes lustres gro up. However , onth e west side of the area , around Corte, a complexse ries of less me tam orphosed rocks occur between theschists and the shea red H ercynian gra nite basem ent tothe west (Fig . 7). In essence much of th is area co nsistsof badly faulted and thrusted fragments of the gra niticbasement with a sedime nta ry cover ran ging fro mTriassic to Eocene in age (th e so called ecaillescortenaises). Th ese are overlain by and fault ed againstseveral nappe units such as the Santa Luc ia nappe.Figure 7 shows a simplified E-W cross sectio n acrossthe a rea N of Corte . Moving from W to E one crosses:

(1) Sheared gra nites and Palae ozoic basem entfaulted aga inst:

(2) Mesozoic lime stones ove rlain by:(3) Eocene clastic sedime nts , all overthrust by:(4) Ligurian ophiolites, faulte d agai nst:(5) The Santa Lucia nappe (granite ove rlain by

looking N

Fig. 7. Cross-section through the Santa Lucie nappe.Numbers refer to locality 3.4 . (after Durand-Delga , 1978).mg = mylonitised granite; ms = mylonitised Palaeozoicmetasediments; Ml = Mesozoic limestones; Es = Eoceneclastic sediments; P = pillow lavas; g = granite basement;c = Tomboni Conglomerate Fm.; ft = Tralonca flysch fm.;sl = schistes lustres .

Eocene clastics) which rests on:(6) more Mesozo ic limeston e and Eocen e clastics

(the para-autochthonous Ca pora lino U nit)which are faulted against :

(7) More ophiolites and the schistes lustres of th eCastagniccia .

Numbers in bracket s refer to those shown on Figure 7.3.5 Th e road to Tra lonca allows an examina tio n ofthe Santa Lucia nappe (5). Leaving the main roa d17 km S of Ponte Leccia at the Colla di San Quilico(559 m) , thi s is whe re the N-S fault run s between theLigurian ophiolit es (4) (ex posed on W side of th ero ad ) and the gra ni te basemen t of the Santa Lucianappe. The gra nite is overl ain by the T omboniCo nglome ra te Formati on which co ntains man y locallyde rived granite frag ments . Stop on the sha rp be ndab out 2 km from the Co l (400 m befor e the Ch ap el ofSan Rocco) to examine these granit ic conglomer at es.Th e granite basem ent itself is exposed 200 m or soback along the road .3.6 Beyond the chapel, the conglome rates pass upint o a seque nce of da rk mudstones and sands to nes ofth e Tralonca flysch formation . Good expos ures of th eflysch are seen along the road towards Tralon ca . Th erocks are fold ed into a broad syncline and displ ayman y minor structures. The flysch , altho ugh lon g heldto be Eocene in age, has nevertheless yie ldedSen oni an micro fossils (D urand-De lga, 1978) .3.7 Ju st beyond Tralonca village park by a sma llgar age (right) to exa mine good el'posures of flyschwith recumbent, sub-isoclinal, stee ply plunging F2

fold s on the ea st lim b of the mai n syncline .3.8 Return to the Co lla di San Quilico and turn Stow ard s Corte . Roadside cuttings in the ecaillescortenaises pro vide exposures of basic lavas (4) whichare thrust ove r E ocen e sandstones (3). Beyond ahairpin bend (1.5 km from th e Co l) are exposures ofMesozoic limeston es-also see n further on, sout h ofBistuglio.3.9 Co rte (79 krn) . Situated in the geographica l andcultura l heart of Corsica, Co rt e has played a centralrole in the island's history. The town is dominated by amajestic citadel, built in 1420 during a short periodof Aragonese sovere ignty. Th e citadel , rec entlyvaca te d by the Foreign Le gion , symbo lises Corte'shistori cal ro le as a ce ntre for resis ta nce . After thebuilding of the cita de l Corte twice suffered captureby the Genoese and in 1734 it was tak en by the Fren chA rmy . Retaken by th e Corsican s in 1745, Co rtebecame the capital of a sho rt lived indep endent nati on(1755 to 1769), when Pascal Paoli esta blished th eisland govern me nt and a uni versi ty.

The old town clings to the steep slope below thecitad el , the slop e emphasising the height of thebu ildings and esp eci ally of the church. The focu s ofthe old town is the Place Pa oli , a small squa redominated by a sta tue of the patriot. At the top of thetown there are fine views from the Belvedere , fro m

CORStCA FIELD M E ETtNG 179

Fig. 8. Cross-section W of Corte along Tavig nano gorge(after du Chaffa ut, 1975). 1 = Hercynian granite ; 2 =

Palaeozoic metasediments ; 3 = Eoce ne clastics; 4 = con­glomerate ; 5 = Liassic limestone ; 6 = schistes lustres .

which one can trace the confluence of the riversTavigano (immediately below) and Re stonica (furtherS). Further west these two rivers cut magnificentgorge s into the Hercynian granite mountain of centralCorsica. At the Belvedere one can also examine thebedrock of ophiolitic schistes lustres (mostly greenbasic volcanics) upon which Corte is built (Fig. 8).

Excursion 4: the Tavignano gorge

The Tavignano and Restonica granite gorges just westof Corte are renowned for their dr amatic scenicbeaut y. Whereas the Restonica go rge is served byroad , access to the Tavignano gorge can only be madeon foot. Th e main features of strictly geologicalinterest are confined only to the first 1.5 krn of thewalk (Fig. 8), beyond which one enters the graniticbasement of Hercvnian Corsica.

Locate the footpath which leaves from the NWcorn er of the town. The path crosses good exposuresof east dipping, strongly folded (and in placesbrecci ated) grey Liassic limestones. Beyond these arepoor exposure s of Cretaceous(?) conglomerates.Further west the actual contact between the graniteand its envelope of finely foliated brown phyllites maybe tr aced across the path . A similar sequence can beseen at the entrance to the Restonica gorge .

Som e of the best scenery may be viewed by walkingfor a further 4 km up the gorge to where the pathmeets the river. The walk can be extended from hereby following the S side of the valley , then climbing Sto the watershed between the two grea t gorges anddropping down into the Restonica gor ge . Howeverthis walk is long, involving a climb to a height of1640 rn, and should only be atte mpted by fit, wellequipped walkers in good weather conditions.

Excursion 5: Corte to Solenzara (85 km)

This excursion moves S from Corte, exammmgexposures of blueschists, sheared gneisses andunmetamorphosed conglomerates along the complexboundary between Alpine and Hercynian Corsica. Theroute then strikes SSW into mountainous forestcountry of the Hercynian granite basement , climbing

looking NW

I ff I f t tr -"-'''--'''--'-'-'''''--"'----'"'----'I'----'"c- __2 _. f + + +

mm @J i mspring km 78

Fig. 9. Roadside section at locality 5. 1. 1 = sheared granite :2 = arago nitic Ju rassic limestones with metabasite ; 3 =sandstone (Eoce ne") : 4 = shea red granite with glaucophanicmeta basite dykes; 5 = conglome rate (Cretaceo us?) .

to 1311 m at the Col de Sorba. Fin ally the roa d turnsE, cro ssing back on to the 'schistes lustres' to rea ch thespectacular ophiolites of the Inzecca Gorge .5.1 Follow the main road S from Cort e for about5 km to a road cutting (right) just beyond a small springfountain (km stone no. 78). The cutting shows a seriesof lithologies juxtaposed by several steep faults (Fig .9) . Most of the section is in sheared granites cut bydeformed met abasic (glaucophanic) dykes. These arefault ed against Jurassic meta-limestones. The meta­limestones are particularly interesting in containingabundant fibrous arago nite- the high P polymorph ofCaCOJ produced during the Alp ine blueschist faciesmet amorphism. The exposure provides a graphicillustration of how in central Corsica blueschist faciesmet amorph osed basement and cover have suffe redintense high angle faulting during the Neogene.Maluski et al. (1973) have emphasised the probableimport ance of sinistral strike slip faulting (noworiented NNW-SSE) along this boundary.5.2 Continue S for another 5 km to a road junctionby a hairpin bend at the Col de Belle Granaje (723 m).Good exposures of stro ngly folded flysch of theBagliacon e-Riventosa Fm . Show strong similarities tothe Tralonca flysch.5.3 1 km beyond Venaco stop at a right bend aftercrossin g beneath the railway. Exposures in the bend ofthe road show sheared Precambrian gneisses cut byHercynian granit es. On Corsica ancient gneisses arepreserved only as large enclaves in several placeswithin the Corsardinian granite batholith : theyrepresent the high grade crystalline basement intowhich the granites were intruded. The exposuresappear to have suffer ed Alpine met amorphism anddeformation .5.4 Fur ther S the Hercynian basement is overlain bythe Vecchio Conglomerate Fm ., thought to be ofCretaceous age. There are many exposures of thes econ glomerates on the W side of the road . The sedeposits provide graphic evidence in favour of theuplift and erosion of the granite basement whichoccurred during the Lower Cretaceous, afte r thedeposition of marine lime stones ea rlier in theMesozoic era .

Fig. 10. Schematic cross-section through the Inzecca Gorge(5.8). 1 = sheared granite; 2 = schistes lustres; 3 = chert;4 = pillow lavas; 5 = serpentinite; 6 = Miocene sediments.

5.5 Beyond Vivario the route leaves the main road tofollow the D69 S, climbing rap idly to an altitude of1311 m at the Col de Sorba . Th ere are superb viewsfrom her e ESE into the Fium 'Orbo Valley. The grandmountain forest scenery is typical of HercynianCorsica. In this area the Carboniferous biot ite granitesare intruded by a circular gabbroic and granitic ringintrusion of Permi an age , although exposures areunfortunatel y rath er poor.

The road descends 700 m to the remote mountainvillage of Gh isoni. Beyond th is the rout e joins theFiurn 'Orbo valley, passing a spectacular abandonedincised meander on the descent towards the coastalplains.5.6 At Pajanello , some 15 km from the Col de Sorba,park by a ruined house. Exposures of acid volcanicrocks (e.g. rhyolites and agglomerates) of Perm ian ageare seen on the N side of the river. Acros s the riverare the ruined mineral workings of Pajanello , onceusing local supplies of argentiferous galena, withsphaelerite, pyrite and chalcopyrite .5.7 Beyond Pajanello the river enters the Stre ttagorge cut through myloniti sed Hercynian granites ,similar to those seen in the Tenda, except that thefoliat ion is vertical. Beyond the gorge one crossesfrom Hercynian to Alpine Corsica, and poorexposures of schistes lustres occur along the roadside.5.8 The road cuts down from the schistes lustresthrough one of the best exposures of Ligurianophiolites in Corsica (Fig . 10). The upper part of thisophiolite dips beneath the schistes lustres andcomprises red radiolarian chert s (well exposed in asmall quarry) underlain by lava breccias and excellentpillow lavas. The se lavas, intruded in places bydolerite , have been deeply incised by the Fium'Orboto produce spectacular exposure s in the Inzecca gorge.Ga bbros are not exposed in the road section , althoughthere are good exposures of serpenti nite beneat h thepillow lavas (Fig. 10).

The road suddenly leaves the mountain country,crossing a fault which brings the Miocene sediments ofthe Aleria plain against the ophiolites and schists ofAlpine Corsic a. The Aleria plain forms the largest partof Corsica's only substantial area of lowland . Untilafte r the 2nd World War the plain was virtuallyuninh abited , being a breeding gro und for malaria andonly used by the hill village rs for winter grazing. Th eroute passes through Ghi sonaccia , the main town on

180

InZ8cca Gorge looking NNE

W . GIBBONS

the plain which owes its recen t development to amajor government spo nsore d land reclamation pro­gra mme which has transform ed the plain. Wa tersto rage in new reservoirs has allowed the irriga tion ofnew plantations won from the maquis and nowgrowing vines, citru s and soft fruit.

Beyond Ghisonaccia the straight. flat road , und er­lain by Quaternary fluvial deposits, crosses back on toHercynian Corsica (Fig. 4) , reaching the S end of theAleria plain at the small port of Solenzara (85 krn). Iftime allows a detour may be made up the Tr avo valley(D645) for 7 km toward s Chisa. Aft er having crossedthe river drive uphill and park by a small gravellygra nite quarry. Th e view across the valley showsautochthonous folded Eocene sediments rest ing uponthe granite basemen t. The Eocene flysch is exposed bya bend a short walk back along the road. Smallexposures of the unconformity between the twounits-a basal nummulitic conglomerate on granite­can be discovered upstream in the river bed below (apath leads down from the bend in the roa d). Returnby the same route , passing good exposures of Eoce neflysch overlain unconform ably by Quaterna ry fluvialconglomerates.

Excursion 6: Solenzara to Bonifacio (92 km)

Th is excursion examines fine exposures of Hercyniangneissic and granitic basement and its cover insouthern Corsica. The route also provides anopportunity to examine the spectacular Mioceneignimbrites and fossiliferous limestones at the extr emetip of the Island.6.1 Drive south towards Porto-Vecchio. Immediatelysouth of Solenzara the plain is pinched out as thegranite basement reaches the coast. The scenery ofthis coastline , although often att ractive , is mut ed incomparison to that of Nand W Corsica. Rainfall ismark edly lower than in the N and the summer droughtis part icularly intense .

Most of S Corsica is composed of Hercynian gra niticbasement , overl ain in places to the east by Eoceneconglomerates, limestones and flysch. N of Sant e­Lucie de Porto Vecchio (25 km S of Solenzara) thegran ite basement is cap ped by a small outlie r ofMesozoic limeston e-the Punta di Calcina (marked bya large television relay ae rial) .6.2 Drive to a small side road (left) signposted toPiccovaggia, 2 km S of Porto-Vecchio. After 7 km oneapproaches the hamlet of Piccovaggia. Take the 2ndroad on the left and park after 100 m on a slight leftbend . Walk SW along a poorly defined path up over acol (note the conglomerate s underfo ot) and follow theovergrown path down for 1 km, skirting a marsh , tothe beautiful, sandy Carataggio beach. The coastalsecti on to the NE provides excellent exposures ofbanded paragneisses cut by red Hercynian granite anddoleri te dykes. Good augen texture is displayed by

CO R SIC A FIELD M E ETIN G 181

Fig. 11. Th e geology around Bonifacio . 1 = Hercyniangranite : 2 = Miocene limestone (afte r Durand-Delga. 1978).

right along a poor . narrow road leadin g to Pert usat olighthou se at the southern tip of Co rsica . A pa th(difficult in places) lead s ea stward s down fro m thelighthou se to a sma ll bay wher e there are supe rbexpos ures of highly fossiliferous cross-bedded Miocenelimeston e restin g upon an irr egul ar surface of pinkH ercynian gra nite . Fossil corals are common on theactual unc onformity sur face .

N. Sard inia , see n across th e water . has a simila rgeology to that of S. Corsica. be ing a conti nua tio n ofthe grea t Co rsa rdinian granite bath olith intrudingPrecambrian gnei ss and overlain locally by sma lloutliers of Miocen e rocks .

If time allows a visit may be made to the Co nvent ofthe Trinit y, situa te d high on a granitic hill from whichare fine views over Bonifacio 4 km to the SE . To reachthis. take the road towards Ajaccio north fromBonifacio , then west. The road (left) to the conventlies some 5 km from Bonifacio.

If a return to Ca lvi is planned , then a recommendedroute is back along the east coast via Aler ia-on e ofthe most famo us archaeologica l sites in Co rsica . Fro mAleri a turn west and follow the Tavigna no river toCorte , initi ally passing excellent expos ures of fossi­liferou s Miocen e marine sediments (ma rls andcon glom erates) affecte d by exte nsiona l low anglenormal faulting. Beyond the Aler ia plain the re areman y exposures of schistes lustres. ofte n ove rla in bycoarse fluvia l deposits of Quaternar y age . No rthwardsfrom Cort e and Ponte Lecci a the roa d to the northcoast runs between the Tenda massif (E) and the mainoutcro p of Hercynian gra nite (W), initi ally crossingthe dominantl y ophio litic rocks of the Balagne . In thisarea the Balagne is allochthon ou s (like the Ne bbiounit-excursion 2). Exposures of Jurassic pillow lavasare see n in many roadside cutt ings (see Durand ­Delga , 1978, p . 150).

At the Co l de San Stefano (692 m) are fine views Nover the Eo ce ne sedimentary rocks of the Balagne.Walk eas t from here along a track to examineinterest ing exposures of olistostromes (left), Terti arymudstones , Jurassic limestones (p rom inent hill).pillow lavas and dark radiolarian cherts overt hr ust byconglomerates of the Altujava Fm . (D urand-D elga,1978, p. 149) .

ACKNOWLEDGEMENTS

Essential help dur ing the G. A . tr ip was provided byD ave Hu ghe s (co -lea de r) , Ja na Horak (sec retary) an dA ndy Bar ker (demonstra to r) . Sincer e tha nks are alsodu e to several ot he r participan ts who gave the leadersinvalu able hel p and sup po rt afte r the deat h of Mr.Grieve, particu larly Gerry Bart ram. J une Knight.Peggy Morris. David and Felicity Williams. theshe phe rds of the Berger ie de Cappe llaccia and . mostof all, Roddy Braith wait e .

++6 .5

BonlfaCiO~

+ ++ + + + + + + + + + +'/--'- --=o::l

+ + + + + + + + + + + +

man y of the gneisses. Foll ow the coast aro und forsevera l hundred metres to reach exposures of coar secongl omerates resting against the gra nite . Thecon glomerates contain clasts not only of granite butalso of Jurassic and Cretaceous limeston es and areprobably of Eocene age .6.3 Return to the main ro ad , drive S for 16 km andturn left along an unmetalled track . Drive eas t alongthe tr ack for 2 km to the coast at Capo Bianco. H er e ,walk S across the beach (on milit ary land) to wherethe unexposed basement is overlain by Miocenesandston es and marl s over which a whit e ignimbritehas been erupted . Superbly fre sh expos ures of thisignimb rite are seen in the low cliffs . Th e ignimb ritehas been dated as 17.8 ± 1.5 Ma (K-Ar) and containsfra gments of pumice and crystals of biotite and quartz.Successive layers of finer material at the base of themain ash flow indicate several mild e ruptions to havepreceded the major one. This exposur e is unique inCorsica , altho ugh similar eruptives are found further Sin Sardinia .6.4 Drive south to Bonifacio . In th is area thegrani te s are overlain by white lime ston e produces aKarstic tablel and more reminiscent of S. Proven cethan Corsica . Th e low ra infall and permeabl e rockmak e th is the 'most desiccated part of the island . andonly a spare and stunted maquis vegeta tion , calledMucchia , cov ers much of the land surfac e .

Bonifacio occupies the mo st rem ark abl e site in theisland , perched on a narrow limeston e peninsula 60 mhigh and 1500 m long (Fig. 11). The W half of thePeninsula is occupied by a citadel , founded in 1195by the Gen oese , and now occupied by the ForeignLeg ion . In the centre of the peninsul a sta nds theHalite Ville, with superb views across the Gulf ofBonifacio to Sardinia . onl y 15 km to the S.6.5 Drive E from Bonifacio and afte r 400 m turn

182 W. GIBBONS

References

ALVAREZ, W., 1972. Rotation of the Corsica-Sardiniamicroplate. Nature, Lond., 235, 103-5.

ARTHAUD, F. & P. MATTE, 1975. Les decrochementstardi-hercyniens du Sud-Ovest de l'Europe. Geometric etessai de reconstitution des conditions de la deformation.Tectonophysics, 25, 139-71.

AUZENDE, J. M., J. BONNIN & J. L. OLIVET, 1973.The origin of the Western Mediterranean basin. 1. geol.Soc. Lond., 129, 607-20.

BOCCALETTI, M. & P. MANETTIE, 1978. The TyrrehianSea and adjoining regions. In (Nairn, A. E. M. & Kanes,W. H., eds.) The Ocean Basins and Margins. Vol. 4B. TheWestern Mediterranean. Plenum Prese, N.Y. p. 149-200.

CHABRIER, G. & G. MASCLE, 1975. Comparaison desevolutions geologiques de la Provence et de la Sardaigne (itpartir d'examples de la region toulonnaise et de la Nurrasarde). Rev. Geogr. Phys. Geol. Dynam., 17, 121-35.

COHEN, C. R., R. A. SCHWEICKERT, O. A. LEROY,1981. Age of emplacement of the schistes lustres nappe,Alpine Corsica. Tectonophysics, 73, 267-84.

DU CHAFFAUT, A. S., 1973. Les relations entre schisteslustres et fiyschs autochtones dans Ie Sud de la Corsealpine. oeot. alpine, 49, 5-12.

-, J-M. CARON, R. DELCEY, & M. LEMOINE, 1972.Donnees nouvelles sur la stratigraphie des schistes lustresde la Corse: la serie de I'Inzecca. Comparisons avec lesAlpes occidentales et l'Appenin ligure. C.R. Ac. Sc.,Paris, 275, 2611-14.

--, J-R. KIENAST, & P. SALIOT, 1976. Repartition dequelques mineraux du rnetamorphisrne alpin en Corse.Bull. Geol. Soc. France, 18, 1179-82.

DURAND-DELGA, M., 1978. Corse. Guides GeologiquesRegionaux. Masson, Paris.

FREY, M., J. C. HUNZIKER, W. FRANK, J. BOCQUET(DESMONS), G. V. DAL DIAZ, E. JAGER, & E.NIGGLI, 1974. Alpine Metamorphism of the Alps. Areview. Schweiz, Miner. petr. M.H., 54, 247-90.

GIBBONS, W. & J. HORAK, 1984. Alpine metamorphismof Hercynian hornblende granodiorite beneath theblueschist facies schistes lustres nappe of NE Corsica. J.Met. Pet., 2, (in press).

HORVATH, F. & H. BERCKHEMER, 1982. Mediterra­nean Back Arc Basins. In (Berckhemer, H. and Hsii, K.J., eds.) Alpine-Mediterranean Geodynamics Series 7. Am.Geophys. Union, 141-74.

vIALUSKI, H., 1976. 4°Ar_39Ar ages of biotites from

Corsica and arguments for Permian age of Alkalinegranitic intrusion. Conirib. Min. Pet., 58, 305-17.

__, 1977. Application de la methode 4IJAr/39Ar auxmineraux des roches cristallines perturbees par lesevenements thermiques et tectoniques en Corse. Thesis.Montpelier, France.

MATTAUER, M., M. FAURE, & J. MALAVIELLE,1981. Transverse lineation and large-scale structuresrelated to Alpine obduction in Corsica. J. Struct. Geol., 3,401-9.

-- & F. PROUST, 1976. La Corse alpine: un modele degenese du mctamorphisme haute pression par subductionde croute continentale sous du material oceanique. C.R.Ac. s«. Paris, 282, 1249-52.

MESSIGA, B., G. B. PICCARDO, & W. G. ERNST, 1983.High-pressure Eo-Alpine Parageneses Developed inMagnesian Metagabbros, Gruppo di Voltri , WesternLiguria, Italy. Contrib. Mineral. Petrol., 83,1-15.

MILLER, H., ST. MUELLER, & G. PERRIER, 1982.Structure and dynamics of the Alps-a geophysicalinventory. In (Berckherner, H. and Hsu, K. J.; eds.)Alpine-Mediterranean Geodynamics. Geodynamics Series7. Am. Geophys. Union, 175-204.

MOULLADE, M., 1978. The Ligurian Sea and the adjacentareas. In (Nairn, A. E. M. & Kanes, W. H., eds.) TheOcean Basins and Margins. Vol. 4B. The WesternMediterranean. Plenum Press, N.Y. p. 67-148.

NAIRN, A. E. M. & M. WESTPHAL, 1968. Possible im­plications of the palaeomagnetic study of late Palaeozoicigneous rocks of Northwestern Corsica. Palaeogeogr.Palaeoclimatol. Palaeocol., 5, 179-204.

ROUTHIER, P. 1956. Etude geologique de la Balagnesedimentaire. Bull. Servo Carte geol. France 54, no. 249, 29.

VAN DEN BERG, J. & J. D. A. ZIJDERVELD, 1982.Palaeomagnetism in the Mediterranean Area. In (Berek­herner, H. and Hsu, K. J., eds.) Alpine-MediterraneanGeodynamics. Geodynamics Series 7. Am. Geophys.Union, 83-112.

WESTPHAL, M., C. BARDON, & R. HAMZEH, 1973. Acomputer fit of Corsica and Sardinia against southernFrance. Earth Planet. Sci. lett., 18, 137-40.

ZACHER, W., 1979. The geological evolution of NECorsica. In: van der Linden, W. J. M. (ed.) Fixism,mobilism or relativism: Van Bemmelen's search forharmony. Geol. Mijnbouw . 58, 135-138.